Why you should never eat from a dish after a fly has landed on it

Picture: File flies’ legs and wings were teeming with hundreds of different species of bacteria

If a fly lands on your carefully prepared picnic, you’re more than likely to swat it away and tuck in anyhow.

But you should never eat from a dish after a fly has landed on it, according to a study. Researchers found that flies’ legs and wings were teeming with hundreds of different species of bacteria, often picked up after they had landed on carcasses or faeces.

These were easily transferred to surfaces when flies landed, with their legs spreading the most microbial organisms. Those who eat food after flies, dubbed “airborne bacteria shuttles” by researchers, had landed on it therefore put themselves at risk of picking up nasty diseases.

Scientists had long suspected flies played a role in carrying and spreading diseases because they were all around us. The team of researchers from Pennsylvania State University, Singapore’s Nanyang Technological University and the Federal University of Rio de Janeiro studied the microbiomes of 116 houseflies and blowflies from three different continents.

The study, published in the journal Scientific Reports, found that in some cases flies carried hundreds of different species of bacteria, many harmful to humans.

These included Helicobacter pylori, a pathogen that often caused ulcers in the gut. City-dwelling flies were found to carry more germs than those in rural areas.

Carrion fly species such as blowflies and house flies were exposed to unhygienic material because they used faeces and decaying organic matter to nurture their young. They could then pick up bacteria that would act as pathogens to humans, plants and animals.